Several important market products, fine or commodity chemicals, are currently produced using step-by-step processes, which require separate reaction units, purification steps and often drastic reaction conditions, with serious economic and environmental drawbacks. The demand is still felt for processes that are easily applicable on industrial scale and that enable one-pot cascade/tandem reaction sequences to provide faster, more environmentally friendly and cost-effective overall transformation of basic substrates into more complex chemicals.
Levulinic acid is a well-known product of hexose acid hydrolysis, and is inexpensively obtained from cellulose feedstocks. Consequently, it is an attractive starting material in producing useful 5-carbon compounds, such as methyltetrahydrofuran and derivatives and 5-methyl-dihydro-furan-2-one, also known as gamma-valerolactone.
U.S. Pat. No. 2,786,852 A (QUAKER OATS COMPANY) 26 Mar. 1957 discloses production of 5-methyl-dihydro-furan-2-one from levulinic acid in vaporized form, suspended in a stream of hydrogen gas, using a reduced copper oxide catalyst at a temperature from 175 to 250° C.
U.S. Pat. No. 5,883,266 A (BATTELLE MEMORIAL INSTITUTE) 16 Mar. 1999 discloses the use of a bimetal catalyst to prepare a variety of products from levulinic acid including 5-methyl-dihydro-furan-2-one at a reaction temperature of 200° C. or 250° C. at an operating pressure of 100 atm.
U.S. Pat. No. 4,420,622 A (STAMICARBON) 13 Dec. 1983 is relative to the preparation of 5-alkyl-butyrolactones using C8 hydrocarbon levulinate esters, with side-chain alkyl substituents of up to 4 carbon atoms as starting material, with the reaction being conducted with hydrogen at a temperature of from 150 to 325° C., in the gas phase, and in the presence of a hydrogenation catalyst composed of metals of Group VIII or Group Ib of the Periodic Table.
U.S. 20040254384 A (DU PONT) 16 Dec. 2004 discloses the transformation of levulinic acid to gamma-valerolactone using a metal catalyst in the presence of a superfluid solvent.
Aim of the present invention is to provide a method for the conversion of readily available starting materials, such as levulinic acid, into advanced intermediates, such as gamma-valerolactone and its derivatives, under relatively mild conditions. Another object of the present invention is to provide a process for such transformations that can be easily scaled to industrial productions and that is cost-effective and environmentally friendly.